you are using the word art very loosely here. It's vague.
If you are talking about the conventional paintings or anything graphic, then yes.
You have more freedom as there are some expressions that cannot be described by words - some languages may have it but in order to understand the word, one must first know the feeling it correlates to.
And that is the discrepancy between audio vs graphic.
Although, if the artist have more freedom to express oneself, the audience may too exercise that freedom and interpret it differently than the artist has intended.
This gives written art more freedom as it is precise. Words are most often defined so to misinterpret is to do so with effort, may it come from the audience or the writer. There are instances where one can misunderstand the statement being delivered. This is due to some people failing to relate rather than to comprehend the message being conveyed. They may have some vague idea as they are familiar with the words but sentence structure are often complex and have deeper meaning to it more than one might think. Take poetry for example.
The degree of freedom of expression solely depends on the artist and whether they have the intention of passing on the message to the audience. Should the intended recipient be only the artist, then it truly is freedom, despite of which method is chosen, may it be written or otherwise.
"How much can the audience understand the message?"
A blank white canvas can say a lot but nothing to most people. "How does that make sense?"
Say that the artist is well-known for the use of colour and abstract images, practically never leaves any blank spot or a block of uniform colour. If the audience knew how this artist operates, they can understand that this white blank canvas being a finished product has a deeper message. A deeper meaning.
We can relate more on this with music. If we were to play the same music with a different tempo, it changes the mood completely despite of having the same content. One can make an originally energetic and cheerful song into a more somber one.
This is why we have people who appear pompous or snobbish to us. They may just know what the artist is truly expressing but we lack the insight to understand so we misunderstand it.